Conventionally, a fuel tank, which is made of resin in place of a metal material such as iron or aluminum, has been developed and is put into a commercial use to reduce a weight of a vehicle such as a motorcycle.
With respect to this type of fuel tank, there has been known a fuel tank that includes a tank body which adopts the multi-layered structure consisting of an outer layer, an intermediate layer and an inner layer, and an insert portion which constitutes a takeout portion of fuel is mounted on the outer layer of the tank body by heat plate welding. Such a configuration is shown, for example, in Japanese Patent Publication JP-A 2002-160537.
In the conventional constitution, although the insert portion is arranged on the outer layer, when forming the outer layer, the insert portion is configured such that a force is hardly applied to the outer layer at an end portion of the insert portion. Accordingly, there exists a possibility that a notch may be formed in a mounting portion of the insert portion to be mounted on the tank body. This notch is an extremely small gap formed in a mounting portion arranged between the insert portion and the tank body due to shrinkage of the outer layer after the insert portion is mounted on the outer layer of the tank body by welding.